As someone else pointed out, AWS does consistently upstream things to OpenJDK and is in fact regularly one of the largest contributors.
Additionally, the entire thing, again, is open source and with a permissive license meaning nothing is stopping anyone from forking it and doing what they'd wish with it.
You are in fact right that it was created to work well with AWS, but I fail to see how that is 'lock in', since most of those benefits are probably benefits on any modern cloud - since AWS does not generally run on a particularly unique architecture.
Additionally, the entire thing, again, is open source and with a permissive license meaning nothing is stopping anyone from forking it and doing what they'd wish with it.
You are in fact right that it was created to work well with AWS, but I fail to see how that is 'lock in', since most of those benefits are probably benefits on any modern cloud - since AWS does not generally run on a particularly unique architecture.